Neuroendocrine peptides, characterized by virtue of hypophysiotropic effects, have been established to be key regulators of anterior pituitary cell functions and growth and also to often have broad significance as regulators of the endocrine and central nervous systems. The goals of this project are directed towards the chemical and biological characterization of neuroendocrine peptides controlling corticotropic and somatotropic pituitary cells. This involves: 1) Purification of novel peptides and characterization of their precursors and genes including the corticotropin releasing factor (CRF) binding protein, peptides derived from the mammalian melanin concentrating hormone precursor and a hypothetical ACTH inhibiting factor. 2) Investigation of the in vivo (with Project V) and in vitro expression of selected neuroendocrine genes, initially CRF. 3) Study of neuroendocrine peptide receptors and the mechanisms of action of peptides such as growth hormone releasing factor (GRF), somatostatin and activin (inhibin BetaBeta dimer) as they regulate the function and proliferation of somatotropic cells. 4) Development of neuroendocrine peptide pharmacology of CRF and GRF in collaboration with Project II to facilitate fundamental studies as well as to provide agents of potential clinical significance.